Revert "Implement ArrayAccess interface for conveniently accessing rcube_result_set as array"

This reverts commit a7d68eaf1a0df1d954b4d6623ff0419a93739cd2.
Revert "Support structured data for autocompletion results; map 'type' attribute to CSS class for autocomplete list items"

This reverts commit e3773d46cb4f06aaab2747db98765edd6d871524.